tRNAs as toxin targets in phage defence and a focus of counter-defence against abortive infection

Abstract

Shutoff of host translation is a common immunity strategy employed by bacteria to defend against predatory bacteriophages. Many bacterial toxin–antitoxin systems specifically target and inactivate tRNAs to achieve translational inhibition, potentially in response to phage infection. Common modes of action include modification, cleavage or re-allocation of target tRNAs. Recent studies have also identified key determinants of specificity for tRNA-targeting toxins. Herein, we discuss toxin action and specificity in the context of phage defence. As a counterpoint, we consider virally encoded tRNAs as counter-defences and drivers of phage evolution.